One method for coupling a pair of optic fibers, to pass a high proportion of light from one to the other, is to melt the ends of the fibers into beads or lenses, and to hold the lenses a predetermined small distance apart and in alignment. When a lens is formed at the end of a fiber, an interface between the lens and the rest of the fiber is formed, which is weaker than the rest of the fiber. To avoid breaking off the lens through handling of it, it is often desirable to first fix the fiber in place on a contact, and to then form the lens on the fiber so the lens ends up at its final position. Whether or not the lens is formed when it is fixed to the contact, the lens must be formed with a rounded forward portion having a predictable radius of curvature and being symmetrical about the axis of that portion of the optic fiber lying just behind the lens where the fiber will be held. A method and apparatus which facilitated a predictable formation of such lenses, especially when held in a contact, would be of considerable value.